SAN JOSE — Defenseman Radim Simek is out long-term with damage to the anterior cruciate and medial collateral ligaments in his right knee, dealing another blow to an already shorthanded Sharks defense corps with a less than a month to go before the start of the NHL playoffs.

Simek, 26, suffered the injury in the first period of Tuesday’s game in Winnipeg and will undergo surgery. No timetable has been set for his return, although it seems unlikely that Simek would be able to come back this season. The Sharks did not specify Thursday if the ligaments in Simek’s knee were torn. His surgery date is still to be determined.

Asked if Simek will miss the rest of the season, Sharks coach Pete DeBoer said, “I don’t know if I’ve heard that yet. He’s done for quite a while. I think it depends on how long we play. But he’s out for a long time.”

The Sharks are already without Erik Karlsson, who continues to recover from a second groin injury he suffered in a Feb. 26 game against the Boston Bruins.

Karlsson said recently he would be back for the start of the playoffs in early April, but wasn’t sure if he could play again in the regular season. Karlsson has not yet started skating again, although DeBoer said his return in that regard is “on the horizon.”

Against the Jets, Simek’s knee was bent awkwardly after Andrew Copp fell on his right leg. Simek spent a few minutes laying on the ice before Brent Burns and Tomas Hertl helped to carry him off.

“It’s not easy to see. We saw the play and it was pretty ugly,” Hertl said Thursday. “He’ll come back even stronger, but it’s for sure bad luck. It’s a tough blow for us because he was playing really good hockey with (Burns).”

Simek’s injury means Joakim Ryan will draw into the lineup for the first time since Jan. 22, when both Karlsson and Marc-Edouard Vlasic were out with injuries. Ryan will play with Burns to start Thursday’s game against the Florida Panthers, as the Sharks begin a three-game homestand.

The Sharks enter Thursday with 94 points, one point ahead of the Calgary Flames for first place in the Western Conference.

“Just try to keep things simple at first, be aggressive and try to take the body as much as possible,” Ryan said. “Try to get into the game in the first 10 minutes and see how it goes from there.”

Simek has played a key role in the Sharks midseason turnaround, stabilizing Burns’ pairing when he joined the lineup on Dec. 2.

The Sharks are 28-9-3 with Simek in the lineup this season. He’s posted a plus-7 rating while averaging 15:33 of ice time.

Ryan is 15 pounds lighter than Simek, and does not necessarily play with the same level of physicality, something that DeBoer loved about Simek’s game.

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It’s clear DeBoer wants Ryan to be somewhat of a physical presence.

“For me, Joakim’s at his best when he’s skating, using his feet and he’s playing with a little bit of physical play,” DeBoer said. “I’m not expecting him to knock people on their (behinds) like Radim does, but you have to have some type of physical element to your game where you’re stopping people. That’s what we’re looking for.”

The Sharks recalled Jacob Middleton from the Barracuda on Thursday to give them seven healthy defensemen, and that organizational depth is obviously proving to be beneficial now.

The Athletic’s Pierre LeBrun tweeted Feb. 25 just before the trade deadline that other NHL teams, looking for depth on defense, were calling the Sharks regarding Ryan. DeBoer, though, said members of the organization felt the Sharks were going to need all eight defenseman “at one point or another if we get where we want to go.”

Ryan said he heard those same rumblings around the deadline, but said Thursday, “that’s something you can’t really worry about, personally. If it happens, it would have happened. But obviously it didn’t, so this is where my focus is and where I want to be.”

Ryan has five assists in 34 games this season, but had fallen behind Simek and Tim Heed in terms of playing time.

“It wasn’t anything like I went up to (general manager) Doug (Wilson) and said, ‘Can you please trade me,’” Ryan said. “Every team wants to have as much depth as possible, especially when you’re looking to go on a long playoff run. I’m sure this is exactly the situation Doug was thinking about.”

▪The Sharks can clinch a playoff spot — their 13th in 14 years — if they defeat Florida and Minnesota loses to Dallas in regulation time in a game that starts at 5 p.m. (PDT) Thursday night. San Jose can also clinch if it defeats Florida, Minnesota earns only one point against Dallas and Arizona loses to Anaheim in regulation time. The Coyotes’ game with the Ducks starts at 7 p.m.

“It’s an accomplishment in this league, it really is,” DeBoer said. “It’s nice to have that out of the way because there’s been a lot of years where we haven’t known for sure until much later than this. It’s nice that we’re also in a hunt for first. That’s important, too, that you still have goals you’re chasing.

“But when we set out at the start of the season, we wanted a ticket to the playoffs because that’s always the first step. Hopefully we can get that accomplished.”

▪ Forward Barclay Goodrow did not take part in the Sharks’ morning skate for maintenance reasons, DeBoer said. He is expected to play against the Panthers.